tree 5b7962ccbc5ecbf93bc0b923fc1b5d4eefcadd77
parent 35ff9b29ba45c2e7ada6c5a279ab9471057aafd7
author Nick Desaulniers <ndesaulniers@google.com> 1548557663 +0000
committer Nick Desaulniers <ndesaulniers@google.com> 1548557663 +0000

lld: elf: discard more specific .gnu.linkonce section

Summary:
lld discards .gnu.linonce.* sections work around a bug in glibc.
https://sourceware.org/bugzilla/show_bug.cgi?id=20543

Unfortunately, the Linux kernel uses a section named
.gnu.linkonce.this_module to store infomation about kernel modules. The
kernel reads data from this section when loading kernel modules, and
errors if it fails to find this section. The current behavior of lld
discards this section when kernel modules are linked, so kernel modules
linked with lld are unloadable by the linux kernel.

The Linux kernel should use a comdat section instead of .gnu.linkonce.
The minimum version of binutils supported by the kernel supports comdat
sections. The kernel is also not relying on the old linkonce behavior;
it seems to have chosen a name that contains a deprecated GNU feature.

Changing the section name now in the kernel would require all kernel
modules to be recompiled to make use of the new section name. Instead,
rather than discarding .gnu.linkonce.*, let's discard the more specific
section name to continue working around the glibc issue while supporting
linking Linux kernel modules.

Link: https://github.com/ClangBuiltLinux/linux/issues/329

Reviewers: pcc, espindola

Reviewed By: pcc

Subscribers: nathanchance, emaste, arichardson, void, srhines

Differential Revision: https://reviews.llvm.org/D57294

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@352302 91177308-0d34-0410-b5e6-96231b3b80d8